The cephalosporin compounds provided by the present invention are those represented by the formula: ##STR2## wherein HO-A- represents a hydroxypyridyl group which may further be substituted with a lower alkyl group, a lower alkoxy group, a lower alkanoyl group, a lower alkoxycarbonyl group, a lower alkylmercapto group, a mercapto group, a hydroxyl group, a lower alkoxymethyl group, a halogen atom, a cyano group, a nitro group, a lower alkylsulfonyl group, an arylsulfonyl group, a sulfamoyl group, a carbamoyl group, an aryloxycarbonylamino group, an acetoacetylamino group, a lower alkylamino group, a lower dialkylamino group, a halogenoalkyl group, an alkenyl group, an aryl group, a cycloalkyl group and a condensed ring cyclo(lower)alkylene group; R.sub.1 and R.sub.2 may be the same or different and each represents a substituent selected from the group consisting of a hydrogen atom, a dialkylamino group, a hydroxyl group, an alkanoyloxy group, a lower alkyl group, a lower alkoxyl group, a halogen atom and a hydroxymethyl group; T represents a group of either one of the formulae: ##STR3## wherein R.sub.3 represents a carboxyl group or a sulfo group, X represents a straight chain or branched chain alkylene group, R.sub.4 and R.sub.5 may be the same or different and each represents a lower alkyl group; and their pharmaceutically acceptable non-toxic salts.
The present invention also provides antimicrobial compositions comprising an antimicrobially effective amount of the cephalosporin compound of the formula (I) or its pharmaceutically acceptable non-toxic salt and a carrier or diluent. It further provides a process for producing the cephalosporin compound of the formula (I).